Gas lift valve



March 28, 1967 w. A. DUDLEY GAS LIFT VALVE Filed Dec. 18, 1965 UnitedStates Patent O 3,311,126 GAS LIFT VALVE Wiliiam A. Dudley, Garland,Tex., assignor to Merla Tool Corporation, Dallas, Tex., a corporation ofTexas Enea nee. is, 1963, ser. No. 331,576 Claims. (Cl. 137-155) Thisinvention relates t-o valves, and more particularly to gas lift valvesof the pilot-operated type.

In pilot-operated gas lift valves a power piston is exposed to casingpressure on one side and selectively to casing and tubing pressure onthe other side in response to opening and closing of a pilot valve, Theposition of the power piston will control the flow through the valve toprovide a gas lift to the production tubing. During gas lift operations,casing pressure will exceed tubing pressure positioning the piston toallow gas flow through the valve into the tubing. When the tubingpressure exceeds casing pressure, it is generally desired that gasshould not flow through the valve into the casing. To prevent such How,reversal prior valves of this type have included a section between theoutlet yof the main valve and the tubing having a spring-loaded dart orback check valve. This included section complicates the valve structureand limits the valve to a larger size than would be necessary if thesection could be omitted. Smallness of size and simplicity of structureare `desirable features in a gas lift valve because of the limite-dspace available in a well bore and the diculty in servicing or adjustinga gas lift valve once `it has been installed in a production well.

Therefore, an `object of the present invention is to pro vide animproved pilot-operated gas lift valve having re` duced size and asimplified structure.

Another object is to provide a pilot-operated gas lift valve including areverse flow check incorporated in the main valve member.

A further object is to provide the main valve member of a pilot-operatedgas lift valve with an annular slide ring assembly cl-osing the valvewhen exposed to reverse pressure differentials.

Another object is to provide the main valve member of a pilot-operatedgas lift valve with a ball check valve and a slide ring assembly toclose the main valve when exposed to reverse pressure differentials.

Still another object is to provide structure in the main valve member ofa pilot-operated gas lift valve preventing flow reversals.

A still further object is to provide a pilot-operated gas lift valveinstalled to conduct gas from a well casing to a production tubinghaving a back ow check valve in the main valve member wherein flow fromthe production tubing to the well casing is prevented.

Still another object is to provide a combined main valve member and backcheck flow valve in a pilot-operated gas lift valve.

Other objects, features and advantages of the invention will be apparentfrom the drawings, the specification and the claims.

In the drawings:

FIGURE 1 is a view partly in vertical section and partly in elevationshowing a valve constructed in accordance with this invention, inoperating position in a tubing string;

FIGURE 2 is a view partly in half-section and partly in quarter-sectionillustrating details of a preferred form of valve embodying thisinvention;

FIGURE 3 is a detail vertical sectional view of the main valve seat, themain valve member and the slide seal ring assembly of this invention,illustrating the opened position of the main valve member and the closedposition of the slide seal ring assembly.

In FIGURE 3 the details of structure of the improve- Patented Mar. 28,1967 "ice ment of this invention are clearly shown, and FIGURES 1 and 2are included to illustrate a typical installation of a pilot-operatedgas lift valve for conducting lift gas from a well casing to theproduction tubing and to illustrate the relationship of the improvementto a pilot-operated gas lift valve.

Referring to FIGURE 3, inlet thimble assembly 11 forms a part of thetubular housing 12 of gas lift valve V. Main valve seat 13 is providedby a downwardly and outwardly facing frusto-conical surface in the lowerend of inlet thimble assembly 11. Main valve member 14 and sliding sealring assembly 15 cooperate with valve seat 13 to control the flow offluid through the valve.

The upper interior of main valve member 14 is bored and threaded toreceive seat member 16 and depending hollow stem 17 of piston 18. Thelower interior of main valve member 18 is bored as at 19 to receive ballcheck valve 20 between shoulders 21 and seat member 16 and has slots 22extending into bore 19. With ball 2t) seated on shoulders 21, a flowpath for fluid flow will be avai1- able through the communicationbetween slots 22 and bore 19 around ball 20. With ball 20 seated on seatmember 16, such flow path through main valve member 14 will be |blocked.

Sliding seal ring assembly 15 surrounds the upper portion of main valvemember 14 and has interior surface 23 slidable on exterior surface 24 ofmain valve member 14. Groove 25 for O-n'ng 26 is postitioned in surface24 to provide a seal between surfaces 23 and 24. Main valve member 14has outwardly and downwardly extending frusto-conical seating surface 27which engages similar surface 28 on ring assembly 15 when main valvemember is in seated position as shown in FIGURE 2. V

Seal ring assembly 15 includes seal member 29 and retainer ring 30 andhas downwardly and outwardly inclined frusto-conical seating surface 31.In closed position of assembly 1S, seal member 29 will engage main valveseat 13, thereby shutting off the ow through main valve seat 13.

As can be seen from FIGURE 3, sliding seal ring assembly 15 is slidableon main valve member 14 and will close main valve seat 13 when exposedto reverse pressure differential, as hereinafter more fully explained.

FIGURE 1 illustrates the valve of this invention in position in the sidepocket generaly indicated as P of mandrel M forming a portion of theflow tubing T. In the form illustrated, the valve is designed forwireline operation. It will be apparent to those skilled inthe art that,by changing the outlet sub 32 to the part commonly used with permanentlyinstalled valves, the valve could be secured to a lug on the exterior ofa mandrel in the conventional manner. Of course, the side pocket packingwould not be utilized, as it would serve no useful purpose.

Tubular housing 12 is provided by a number of housing parts for easyassembly. Beginning at the bottom of the valve, the lowermost part isthe bottom sub or cap 32. Above the sub 32 is a packing adapter 33 whichis connected to the lower end of the inlet thimble assembly 11. Abovethe thimble assembly 11 is the valve seat housing 34 which is connectedto the lower end of spring housing 35. The upper end of the housing iscompleted by bellows adapter 36.

A fluid inlet is provided in the housing at 37 in inlet thimble assembly11. Preferably, a number of inlet ports 37 are provided and this sectionof inlet thimble assembly 11 is surrounded by a screen 38 to screen outtrash from the ow stream.

An outlet 39 is provided in bottom cap 32 and, as shown in FIGURE l,communicates through port 40 with the interior of flow tubing providedby mandrel M. Inlet screen 38 is located with respect to side pocket Pwhere it communicates with opening 41 so that the fluid from the casingannulus may pass from opening 41 to the inlet 37 of the valve.

A flow passageway connects the inlet and outlet to convey uid from thecasing into the tubing mandrel M. This passageway is provided by a borei2 in inlet thimble assembly 11, a bore 43 through lower packing adapter33 and a bore 44 through bottom cap 32.

As previously described, valve seat 13 is provided in the interior ofinlet thimble assembly 11 and cooperates with main valve member 14- insliding seal ring assembly to control the flow of fluid through theabove-described flow passageway.

Control of main valve member 14 is provided by a power assembly. Thepower assembly is provided by a cylinder 45 in the valve seat housing 34and piston 18 reciprocal in cylinder 45.

The cylinder 45 is exposed at its lower side to casingV pressure throughthe bumper assembly indicated generally at 46. The upper end of cylinder45 is closed providing a chamber 47 above the piston 18.

As hereinbefore mentioned, piston 18 is connected to main valve member14 through stem 17 so that movement of the piston will effect movementof main valve member 14.-' It will be noted that the large end of piston18 has a smaller diameter than the diameter of cylinder 45.

The piston assembly includes a piston 18 having a rigid frusto-conicalperiphery 49 with the small end 50 thereof facing main valve member 14.

The seal for the piston assembly is provided by an annular seal member51 mounted on piston member 18. This seal member is preferably made froma material having a low co-eicient of friction which permits it toAprovide a seal of very light frictional forces. A material such aspolytetrafluoroethylene, commonly known as Teflon may be used for thisseal. Seal member 51 is formed with an inner frusto-conical wall 52 toconform to the outer periphery 49 of piston 18. Seal member 51 has anouter cylindrical wall 53 to conform to the wall of cylinder 45.

VPreferably the angle of the frusto-conical wall 49 on vpiston member 18is suflicient to be self-releasing from seal member 51 to avoid stickingof the seal member to the piston. It is also preferred that the outerdiameter of seal member 51 be slightly larger than the diameter lofcylinder 45 yto give a slight pre-loading of the seal member against thecylinder.

Means are provided for urging seal member 51 upward toward the large endof piston member 18. A bumper washer 54 bears against the lower end ofseal member 51 and spring 55 is held in compression between bumperwasher 54 and an inwardly extending ange 56 within inlet thimbleassembly 11. The force of spring 55 is suicient to provide a slightplastic flow of seal member 51 to effect mating between seal member 51and piston 18.

Bumper assembly 46 is positioned in the path of seal member 51 yas itmoves toward open position of main valve member 14. The bumper assemblyis provided by bumper Washer 54, a bumper member 57 and resilient meanssuch as bumper rubber 58 supporting bumper lmember 57 in the path ofbumper washer 54 as piston 18 moves toward open position of main valve14. The upper lend of bumper member 57 has a surface 59 adapted toengage the downwardly facing surface 60 of bumper washer 54 when piston18 `moves down. As these parts are engaged, the bumper rubber 5S, whichis confined between valve seat housing 34 and sleeve 61 depending frombumper member 57, is compressed. It will be noted that the connement ofthe bumper rubber between the sleeve and housing is such as to permit itto move substantial distance in a radial dimension before completelylling the cavity between the sleeve and the housing. In this manner asubstantial travel of the piston is permitted While the bumper assemblyand the spring 55 build up resistance to downward movement of thepiston. As soon as the bumper rubber 58 is completely compressed,downward movement of the bumper member 57 is substantially arrested. Byhaving this arresting movement transmitted from the bumper memberthrough the bumper washer 54 to seal member 51, the frictionalengagement of the seal with the cylinder is increased to thereby absorba portion of the energy of the downwardly moving piston. 1t has beenfound that this arrangement of transmitting the impact force of thepiston rubber will result in imbedding in the rubber of any particleswhich were too small to be wiped from the cylinder wall. This imbeddingwill minimize scoring of the cylinder wall.

The upper extremity of the cylinder wall is provided with an enlargeddiameter section 62. This results in a shoulder 63 which acts as a wiperto wipe solid particles from the exterior seal member 51. The solidparticles may be trash, or may be salts which tend to build up in somewells.

The piston 18 is constructed in a manner to direct any solid particleswhich appear in the chamber 47 above the piston on through the valve.

It is conventional in valves of the type illustrated to have a bleedport 64 which extends through the piston 18, stem 17 and main valvemember 14 to place the upper end of cylinder in communication with thepassageway through the valve downstream of the main valve seat 13. Inorder to direct trash through this bleed passageway, the upper end ofpiston 18 is dished in, as shown at 65, so that any particles of trashfalling on the top of the piston will tend to be directed to the bleedpassageway.

To permit free passage of trash, the bleed passageway should be as largeas possible. On the other hand, the size of this passageway controls thespeed with which the piston will snap the main valve member to full openposition. For this reason, the bleed passageway through piston 18 andstem 17 is made large and a depending member 66 extends into the inletof the bleed passageway. The length of the member V is such that it willeffectively reduce the size of the bleed passageway until the main valvemember 14 is almost in fully `open position. As the the main valvemember moves to fully open position, the piston 18 will move below thedepending member 66 to clear the bleed passageway and open up the inletto the bleed passageway to thus permit any trash to freely move into thebleed passageway and pass through the valve. It will be noted that thereis a reduced diameter section 67 in passageway 64. This section isprovided to control the ow through the passageway 64 without providingany extensive length of small ow area which could cause a blocking ofthe passageway with trash.

From the valve as thus far explained, it is apparent that the lower faceof the control piston is always exposed to casing pressure and the upperface of the piston is always exposed to the pressure in the tubing. Inaccordance with conventional construction of valves of this type, apilot valve indicated generally at 68 is provided for selectivelyadmitting casing pressure to the closed end of cylinder 45 to thusselectively increase the pressure above the piston to casing pressure.An inlet into the pilot valve is provided by port 69 in valve seathousing 34. Valve seat '712' is supported on valve seat housing as shownand provides outlet ports 71 into chamber 47 above piston 18. The port69 communicates with the spring housing 35 so that casing pressure willbe applied to the bellows 72. Valve seat is provided with O-.ring seal73 to prevent flow of casing pressure from port 69 into chamber 47 otherthan through valve seat 70. Pilot valve 68 is provided with a sphericalplug 73 seating on valve seat 7 t? and valve stem 74. Means are providedfor resiliently urging the valve stem toward seat 70. This means mayinclude the spring 75 held under compression between jam nuts '76 onvalve stem '74 and the lower extremity of upper bellows adapter 36. Alsoincluded in the means for resiliently urging the valve stem '74 towardsthe seat is the bellows 72 connected to the valve stem and exposed tothe pressure fluid above seat 70.

In operation the valve V is run into the tubing which includes themandrel M on a wire line. The wire line is attached to a wire line latchassembly, a portion of which is indicated generally at 77 in FIGURE 1.The valve is run into the side pocket P and landed in the position shownin FIGURE 1 in which the upper and lower spaced seals 78 and 79,respectively, will seal between the valve and the side pocket above port69 and below port 37 on the valve and above and below inlet 41.Thereafter, the production fluids within the well may be lifted by gasintroduced through the gas lift valve in the conventional manner. Thepilot valve will be set to open at a selected casing pressure. Undernormal operations casing pressure will be exerted against bellows 72causing valve 68 to open allowing casing pressure into chamber 47 abovepiston 18 thereby causing downward movement of piston 18 opening mainvalve 14. When main valve 14 is open casing pressure enters throughscreen 38 and ports 37, ows through inlet thimble 11, bore 43 in packingadapter 33, bore 44 in outlet sub 32 and out through ports 39 and 40into the tubing to provide a gas lift for the producti-on within thetubing T.

When pilot valve 68 closes flow of lluid under casing pressure will beblocked and the pressure in chamber 47 will be dissipated throughpassageway 64 causing valve 14 to close.

It for any reason while valve 14 is open a sudden surge of pressurewithin tubing T increases the tubing pressure 4to a pressure above thecasing pressure then such pressure reversal will cause sliding seal ringassembly 15 to close and ball check valve 22 will move upward intoengagement with seat member 16 thereby blocking passageway 64 andcausing main valve member 14 to move upwardly and close.

In certain instances in the production of uid from a well the tubingpressure may gradually rise to be larger than the casing pressure. Insuch an instance as soon as the tubing pressure increases to a valuegreater than casing pressure, sliding seal ring assembly 15 will moveupwardly to engage seat 13 on inlet thimble assembly 11 but ball checkvalve 20 will remain seated on shoulder 21 allowing the tubing pressureto be transmitted to the passageway 64 into chamber47 within cylinder 45above piston 18. This will cause piston 18 to remain in the downwardposition holding main valve member 14 open. However, in this positionwith sliding seal ring assembly 1S closed, no fluids will ow throughvalve seat 13, if tubing pressure builds up gradually to a pressurewhich is suficiently high to open pilot valve 68 by exerting a pressureon spherical plug 73 through valve seat 70. The instant that sphericalplug 73 raises oif seat 70 there will be a ow through the passageway 64which will cause ball check valve 20 to move upwardly into engagementwith seat 16 thereby preventing further ow and causing valve member 14to move upwardly into the closed position.

From this it can be seen that the main valve member of a pilot operatedgas lift valve may be constructed in accordance with the presentinvention to provide a closing of the main valve member whenever theIpressure downstream of the valve seat for the main valve memberincreases above the upstream pressure regardless of whether such excesspressure is rapidly or slowly built up. This is accomplished by thenovel construction of the main valve me-mber. By including suchprovision in the structure of the main valve member the overall size ofthe gas lift valve may be smaller than a gas lift valve having aseparate back llow check valve.

The foregoing disclosure and description of the invention isillustrative and explanatory thereof, and various chan-ges in themethod, as well as in the details of the illustrated construction, maybe made within the scope of the appended claims without departing fromthe spirit of the invention.

What is claimed is:

1. A gas lift valve, comprising a tubular housing,

a main gas passageway through said housing,

a valve seat surrounding said passageway,

a pressure responsive power assembly mounted in said housing,

a seal assembly adapted to engage said valve seat to control ow throughsaid passageway,

means slidably connecting said seal assembly to said power assembly tomove said seal assembly into engagement with said Valve seat,

said seal assembly being free to move into engagement with said seatindependent of said power assembly,

a Ipilot gas passageway connecting to said power assembly,

pilot valve means mounted in the housing and controlling tlow throughsaid pilot gas passageway,

a bleed passageway connecting the -main gas passageway downstream ofsaid valve seat with said power assembly, and

an excess ilow valve mounted in said bleed passageway to prevent excessow through said bleed passageway to said power assembly.

2. A gas lift valve according to claim 1 wherein said bleed passagewayextends through said seal assembly and connecting means to said powerassembly and said excess ow valve is mounted in the end of said Ibleedpassageway in the main gas passageway.

3. A gas lift valve having a main valve mem-ber controlling flow throughthe valve, a piston member reciprocating in a cylinder for controllingopening and closing of the main valve in response to opening and closingof a pilot valve, and a bleed passageway extending through said pistonand said main valve member, the improvement comprising an excess owvalve in said bleed passage, and

said main valve member includes a sliding, seal ring assembly movable tocoact with said piston member in controlling flow through the valvemember in one direction, and responsive to pressure downstream tocontrol ow through the valve independent of said piston member.

4. A gas lift valve comprising,

a tubular housing,

a main gas passageway through the housing,

a main valve seat across said passageway,

a cylinder in the housing having one end closed and one end exposed tothe exterior of the housing,

a piston member reciprocal in the cylinder,

a valve member connected to said piston member and engageable with saidvalve seat for controlling flow through said passageway, a portion ofsaid valve member movable independent of the lmovement of said pistonmember to engage said valve seat responsive to a build-up of pressuredownstream of said valve seat in said main gas passageway higher thanthe pressure upstream of said main valve seat in said main gaspassageway,

a pilot gas passageway connecting the closed end of the cylinder withthe exterior of the housing,

a Apilot valve means mounted in the housing in controlling flow throughsaid pilot gas passageway,

a bleed passageway connecting the closed end of the cylinder with themain gas passageway downstream of the main valve seat, and

an excess of flow valve lmounted in said bleed passageway to preventexcess ow through said bleed passageway to said closed end of saidcylinder.

5. A gas lift valve according to claim 3 wherein said bleed passagewayextends through said piston and said main valve member and extends in agenerally vertical direction, and including a valve seat deiined in thelower end of said bleed passageway,

a ball valve, and

means securing the ball valve in the lower end of the passageway,

said ball Valve adapted to engage said seat in said bleed passagewaywhen the ow through the bleed passageway to the closed end of saidcylinder exceeds a predetermined rate of ow.

References Cited by the Examiner UNITED STATES PATENTS Ford 137-496 XRClifford 137-533.27 XR Tweedle IS7- 489.5 Dudley 137-155 -Ottestad251-77 XR ALAN COI-IAN, Primary Examiner.

1. A GAS LIFT VALVE, COMPRISING A TUBULAR HOUSING, A MAIN GAS PASSAGEWAY THROUGH SAID HOUSING, A VALVE SEAT SURROUNDING SAID PASSAGEWAY, A PRESSURE RESPONSIVE POWER ASSEMBLY MOUNTED IN SAID HOUSING, A SEAL ASSEMBLY ADAPTED TO ENGAGE SAID VALVE SEAT TO CONTROL FLOW THROUGH SAID PASSAGEWAY, MEANS SLIDABLY CONNECTING SAID SEAL ASSEMBLY TO SAID POWER ASSEMBLY TO MOVE SAID SEAL ASSEMBLY INTO ENGAGEMENT WITH SAID VALVE SEAT, SAID SEAL ASSEMBLY BEING FREE TO MOVE INTO ENGAGEMENT WITH SAID SEAT INDEPENDENT OF SAID POWER ASSEMBLY, A PILOT GAS PASSAGEWAY CONNECTING TO SAID POWER ASSEMBLY, PILOT VALVE MEANS MOUNTED IN THE HOUSING AND CONTROLLING FLOW THROUGH SAID PILOT GAS PASSAGEWAY, A BLEED PASSAGEWAY CONNECTING THE MAIN GAS PASSAGEWAY DOWNSTREAM OF SAID VALVE SEAT WITH SAID POWER ASSEMBLY, AND AN EXCESS FLOW VALVE MOUNTED IN SAID BLEED PASSAGEWAY TO PREVENT EXCESS FLOW THROUGH SAID BLEED PASSAGEWAY TO SAID POWER ASSEMBLY. 